Changeset 197308 in webkit

Timestamp:

Feb 28, 2016 9:26:05 PM (8 years ago)

Author:

akling@apple.com

Message:

Make JSFunction.name allocation fully lazy.
<​https://webkit.org/b/154806>

Reviewed by Saam Barati.

We were reifying the "name" field on functions lazily, but created the string
value itself up front. This patch gets rid of the up-front allocation,
saving us a JSString allocation per function in most cases.

• builtins/BuiltinExecutables.cpp:

(JSC::createExecutableInternal):

• bytecode/UnlinkedFunctionExecutable.cpp:

(JSC::UnlinkedFunctionExecutable::visitChildren):

• bytecode/UnlinkedFunctionExecutable.h:
• runtime/CodeCache.cpp:

(JSC::CodeCache::getFunctionExecutableFromGlobalCode):

• runtime/Executable.h:
• runtime/JSFunction.cpp:

(JSC::JSFunction::reifyName):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• builtins/BuiltinExecutables.cpp (modified) (1 diff)
• bytecode/UnlinkedFunctionExecutable.cpp (modified) (1 diff)
• bytecode/UnlinkedFunctionExecutable.h (modified) (3 diffs)
• runtime/CodeCache.cpp (modified) (2 diffs)
• runtime/Executable.h (modified) (1 diff)
• runtime/JSFunction.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2016-02-28  Andreas Kling  <akling@apple.com>
+
+        Make JSFunction.name allocation fully lazy.
+        <https://webkit.org/b/154806>
+
+        Reviewed by Saam Barati.
+
+        We were reifying the "name" field on functions lazily, but created the string
+        value itself up front. This patch gets rid of the up-front allocation,
+        saving us a JSString allocation per function in most cases.
+
+        * builtins/BuiltinExecutables.cpp:
+        (JSC::createExecutableInternal):
+        * bytecode/UnlinkedFunctionExecutable.cpp:
+        (JSC::UnlinkedFunctionExecutable::visitChildren):
+        * bytecode/UnlinkedFunctionExecutable.h:
+        * runtime/CodeCache.cpp:
+        (JSC::CodeCache::getFunctionExecutableFromGlobalCode):
+        * runtime/Executable.h:
+        * runtime/JSFunction.cpp:
+        (JSC::JSFunction::reifyName):
+
 2016-02-28  Andreas Kling  <akling@apple.com>
 

trunk/Source/JavaScriptCore/builtins/BuiltinExecutables.cpp

@@ -110 +110 @@
     VariableEnvironment dummyTDZVariables;
     UnlinkedFunctionExecutable* functionExecutable = UnlinkedFunctionExecutable::create(&vm, source, metadata, kind, constructAbility, dummyTDZVariables, DerivedContextType::None, WTFMove(sourceOverride));
-    functionExecutable->setNameValue(vm, jsString(&vm, name.string()));
     return functionExecutable;
 }

trunk/Source/JavaScriptCore/bytecode/UnlinkedFunctionExecutable.cpp

@@ -117 +117 @@
     visitor.append(&thisObject->m_unlinkedCodeBlockForCall);
     visitor.append(&thisObject->m_unlinkedCodeBlockForConstruct);
-    visitor.append(&thisObject->m_nameValue);
 }
 

trunk/Source/JavaScriptCore/bytecode/UnlinkedFunctionExecutable.h

@@ -77 +77 @@
     const Identifier& name() const { return m_name; }
     const Identifier& inferredName() const { return m_inferredName; }
-    JSString* nameValue() const { return m_nameValue.get(); }
-    void setNameValue(VM& vm, JSString* nameValue) { m_nameValue.set(vm, this, nameValue); }
     unsigned parameterCount() const { return m_parameterCount; };
     SourceParseMode parseMode() const { return static_cast<SourceParseMode>(m_sourceParseMode); };
@@ -163 +161 @@
     Identifier m_name;
     Identifier m_inferredName;
-    WriteBarrier<JSString> m_nameValue;
     RefPtr<SourceProvider> m_sourceOverride;
 
@@ -169 +166 @@
 
 protected:
-    void finishCreation(VM& vm)
-    {
-        Base::finishCreation(vm);
-        m_nameValue.set(vm, this, jsString(&vm, name().string()));
-    }
-
     static void visitChildren(JSCell*, SlotVisitor&);
 

trunk/Source/JavaScriptCore/runtime/CodeCache.cpp

@@ -188 +188 @@
         return nullptr;
     
+    metadata->overrideName(name);
     metadata->setEndPosition(positionBeforeLastNewline);
     // The Function constructor only has access to global variables, so no variables will be under TDZ.
@@ -193 +194 @@
     UnlinkedFunctionExecutable* functionExecutable = UnlinkedFunctionExecutable::create(&vm, source, metadata, UnlinkedNormalFunction, ConstructAbility::CanConstruct, emptyTDZVariables, DerivedContextType::None);
 
-    functionExecutable->m_nameValue.set(vm, functionExecutable, jsString(&vm, name.string()));
-
     m_sourceCode.addCache(key, SourceCodeValue(vm, functionExecutable, m_sourceCode.age()));
     return functionExecutable;

trunk/Source/JavaScriptCore/runtime/Executable.h

@@ -668 +668 @@
     const Identifier& name() { return m_unlinkedExecutable->name(); }
     const Identifier& inferredName() { return m_unlinkedExecutable->inferredName(); }
-    JSString* nameValue() const { return m_unlinkedExecutable->nameValue(); }
     size_t parameterCount() const { return m_unlinkedExecutable->parameterCount(); } // Excluding 'this'!
     SourceParseMode parseMode() const { return m_unlinkedExecutable->parseMode(); }

trunk/Source/JavaScriptCore/runtime/JSFunction.cpp

@@ -590 +590 @@
     ASSERT(!hasReifiedName());
     ASSERT(!isHostFunction());
-    JSValue initialValue = jsExecutable()->nameValue();
     unsigned initialAttributes = DontEnum | ReadOnly;
     const Identifier& identifier = exec->propertyNames().name;
-    putDirect(vm, identifier, initialValue, initialAttributes);
+    putDirect(vm, identifier, jsString(exec, jsExecutable()->name().string()), initialAttributes);
 
     rareData->setHasReifiedName();